If Cov(x,y) = ?350 $s _ { x } ^ { 2 }$

Multiple Choice

If cov(x,y) = ?350, $s _ { x } ^ { 2 }$ = 900 and $s _ { y } ^ { 2 }$ = 225, then the coefficient of correlation is:

A) 0.8819.
B) 0.7778.
C) ?0.0017.
D) 0.0017.